The present invention relates to an information recording medium comprising an information recording layer, which has a liquid crystal phase and a resin phase, and in particular to an information recording medium, in which information recorded on the information recording medium can be easily erased and the same information recording medium can be repeatedly used. The invention also relates to an information recording apparatus using such an information recording medium.
The present applicants have previously proposed an information recording medium, and an information recording apparatus and an information recording method using said information recording medium in Japanese Patent Publications Laid-Open 5-165005 and 6-130347. This information recording medium in the previous applications has an information recording layer laminated on an electrode, said information recording layer is formed by a polymer dispersion type liquid crystal, which comprises a resin phase and a liquid crystal phase. Using a UV-setting resin as the resin phase of the information recording layer, the UV-setting resin particles are filled and dispersed in the liquid crystal phase and surface of the information recording layer is used as a skin layer of the UV-setting resin. The invention also provides an information recording apparatus and an information recording method, in which said information recording medium is placed face-to-face to an optical sensor having a photoconductive layer laminated on an electrode, and by image exposure and voltage application, an image is formed on the information recording medium.
Further, to reproduce the recorded information after information has been recorded, an information recording apparatus having an information reproducing unit on it was also filed as Japanese Patent Application 6-119053. Also, an information recording apparatus having a mechanism to erase the recorded information by heating has been proposed.
In the information recording layer as described above, the surface is formed by a resin layer only. As a result, no bleeding phenomenon of the liquid crystal occurs, and noiseless recording can be performed in the information recording using a photoelectric sensor. Because this information recording layer retains the recorded information after the voltage applied on the electrode has been removed, the liquid crystal phase contains liquid crystal with smectic property to a great extent, and an information recording medium having an information recording layer to stably maintain the recorded information has been used. Taking an example, a liquid crystal mixture is used, which contains a liquid crystal having nematic property and a liquid crystal having smectic property in mixing ratio of 5/95-20/80.
However, strong memory property is generated and continuously retained unless it is heated above the isotropic phase transition temperature, and it is necessary to heat to higher than the isotropic phase transition temperature in order to erase the recorded information and to repeatedly utilize the same information recording medium. For this reason, in an information recording apparatus using the above information recording medium, it is necessary to provide a heating mechanism, which can heat the information recording medium sufficiently to erase the recorded information because the information recording medium has strong memory property and the information recording medium is repeatedly used by erasing the recorded information.
It is an object of the present invention to provide an information recording medium, by which it is possible to record information by an electrode laminated on an information recording layer by information exposure, to easily erase the recorded information, and to repeatedly use it as the information recording medium.